There are plenty of bags with built-in speakers, but most of them are trying too hard to look like they're normal bags and not just big glorified iPod cases. I don't know anyone who'd carry a speaker bag as their everyday purse, so why not just cheese it up and use the iPod Tote that looks like an old Fisher Price record player. The bag can connect to any music player with a headphone jack and includes an FM radio with soft controller buttons on the front. The stereo speakers are amplified so you can probably play DJ in a moderately-sized room. A thrill for all your friends, I'm sure. The bag takes 4 AA batteries. $60 from fredflare.